Constructively, maybe if the protestors do "overrun" the cops, then the protestors could setup a new justice system, arrest the criminal conspiracies, and try them under RICO. If there were enough protestors willing to work this justice system, it could even be a good time for cities to say farewell to the incumbent union and hire the new system to keep order instead.
But practically yes I agree things will get ugly if we keep going down this path. But since the police are over the line by aggressing against basic American values, the only peaceful resolution is for them to simply stand down and stop attacking protests. I don't see any other option that wouldn't be bargaining with totalitarianism.